This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Advances in crop science and biotechnology have led to specialty crops that have one or more desirable traits. Examples of such traits include, drought-resistance, pesticide tolerance (e.g., glyphosate tolerance), high-yielding crops, seeds with desirable fatty-acid profiles (e.g., as in low-linoleic acid soybeans), high-oil seeds, insect tolerance (e.g., corn-bore resistance) and the like. There is an increasing need to test commodity crops to determine whether they possess altered DNA sequences that express such traits. Biotech products may be analyzed by testing for proteins that are expressed by the modified DNA sequences. However, such techniques are not capable of distinguishing between plant varieties that produce the same recombinant proteins. In such instances, the plant is tested by analyzing whether the plant DNA contains the specific DNA sequence that results in expression of the trait.
Conventionally, these DNA sequences are detected by gathering a sample and transporting the sample to an off-site laboratory. The sample may be processed by extracting template DNA and amplifying the DNA by polymerase chain reaction (“PCR”) techniques. PCR amplifies template DNA by use of two oligonucleotide primers, an agent for polymerization, a target nucleic acid template and successive cycles of denaturation of nucleic acid and annealing and extension of the primers to produce a large number of copies of a particular nucleic acid segment. With this method, segments of single copy genomic DNA can be amplified more than 10 million fold with very high specificity and fidelity. PCR typically requires thermocycling equipment and equipment to monitor reaction kinetics if detected in real-time. Typically, secondary equipment (e.g. fluorescence detector) and methods (e.g. gel electrophoresis) are used to detect amplified DNA after the conclusion of amplification. This equipment is bulky and requires technical skill to operate, which prevents the equipment from remote-use applications (e.g., point-of-grain delivery) by unskilled users.
As an alternative to PCR techniques, an analysis method known as recombinase polymerase amplification (RPA) has been developed. RPA techniques can amplify a single copy of DNA and can amplify DNA under generally isothermal conditions. Moreover, RPA analysis can be performed in about 15 minutes and does not require sample purification. While RPA analysis may be preferred over PCR analysis, RPA conventionally is also performed in a laboratory by highly trained personnel. Typically the equipment used for analysis is capable of analyzing a number of samples (e.g., well plates) which results in the equipment being bulky and of limited portability. Further, the equipment is of high complexity (e.g., uses sophisticated mixing techniques and programmable software) which results in increased cost. A continuing need exists for portable and simplified instruments and methods for detecting nucleotide sequences (i.e., genes, markers, molecular events) in plants (e.g., soybeans) and equipment and, particularly, systems that use RPA amplification.